Sonobuoys are commonly deployed in the ocean by suspending the sonobuoy from a float at the surface of the ocean so that the sonobuoy is located at a point beneath the surface of the ocean. In the case of sonobuoys deployed from aircraft, the upper portion of the buoy housing is frequently provided with a parachute for controlling the speed of drop through the air, the housing further including a float plus a float expansion device, such as a cylinder of a compressed gas, which is activated upon contact with the water whereupon the buoy is suspended from the float.
A problem arises in that sonobuoys may carry a transducer, or array of transducers for transmitting and/or receiving sonar signals in predetermined directions. To provide a reference axis for determining these directions, it is desirable to maintain a longitudinal axis of the sonobuoy in a vertical direction during descent to a predetermined depth and during deployment at the predetermined depth. However, it has been found that with buoy suspension systems of the prior art, the action of the wave motion as well as differential velocities between horizontal strata of the ocean water upon the float and upon the buoy in concert with the tension of the cable securing the buoy to the float introduces a rocking motion to the sonobuoy with a resultant continuous variation in the orientation of the longitudinal axis about a vertical direction.